Luminous hair-line.



' a Umiinnlstra'rns PATENT OFFICE.

connu x'mnmcm or wAsmNoroN, 4msrmc'i: on commen. LUmNoUs 1mm-LINE.

Q 1,3o2,353. specimen erwten ment Patented Apr. 2a, 191e.

application inea september zo, 1917. serial No. 192,365.

To all whom z't may concern Be it known that I, CONRAD FRIEDRICH, a. citizen of the United States, residing at Washington, in the District of Columbia,

have invented certain new and useful Improvements in Luminous Hair-Lines, of which the following is a s ecieation.

The present inver on re ates to hair-lines for optical instruments. It is well known 1 that in optical instruments for establishing definite lines between a point of observation and distant objects ythe conventional crosshairsacting as fiducial lines are not suited for observations at right. This defect has been remedied by the application of special illuminating devices comprising a battery or other source of electricity, an electriclight bulb, electric connections and-somecoinplete satisfaction for 'the purpose/for which they are designed, they have the disadvantage that the operation of the optical instrument depends on outside factors which may fail at any momentandy make the instrument useless.

This invention has for vits general object the provision of means for visualizing-symbols, lines of reference or other lines of demarcation on a transparent body which, -in the absence of a sufficient quantity of li ht .passing it, are normally not visible.

lie more particular object ofthe invention is the provision of a luminous hair-line 35 system which is self-contained within an optical'instrulnent and not liable to become suddenly inoperative.

Another obj ect of the invention's the provision of a liair-line s stem that may be used '4o by day and night wit out any change on the instrument or any action on the part ofthe observer.

I accomplish the purpose and attain the'I objects of the invention by providing' on. a,

v4|; glass plate or other transparent body means l for defining a hair-line or hair-lines of such characteristics as to be distinctly visible.- when illuminated by a radium-luminous ma? Y terial, radium-luminous compound or other. luminous radio-active material.,

For a fuller understanding of the invention reference is had to the appended draw ings in' whichf Figure 1 shows the application of my im t5 vention to 4a telescope;

lthe hair-lines preponderates to such an cx- 'tent that they stand outdistinctly by oon- ...trast and perform their function as liairlines or cross-hairs as efficiently as b day.

influence of radium-lumiiious material in va- Fig. 2 one form of the device embodying the invention' A 3 another form thereof;

Figs. 4 and 5 modifications of the form shown in Fig. 3; 60

Fig. 6 another modiication thereof; and i Fig. 7 illustrates a method for forming the hair-lines on a glass plate.

In Fig. 1, which represents the ocular end of a telescope, 1 is the main tube of the tele- 55 scope. 2 the ocular tube` 8 the adjustable section thereof carrying the lenses 4 and 5 und a circular glass plate or other transparent disk fixedly'supported in the tube This plate (S- isnuiuuled in u ring S as is usual, and the position is such that/for the normal position of the adjustable section the glass h 4plate is substantially in the focal plane of times light ray modifying nieanshsuch'as 20 lprisms and lenses. While such devices givetheleus system 4, 5. I preferably provide hair-lines or cross-lines by forming grooves 7 of exceedingly small width and deiitli in the face of plate 6.

I have found that when such grooves are brought under the influence of radium in the form of luminous radium salts or raj diuin-luininous compounds, as for instance zinc sulfid mixed with radium, they emit light rays and appear to the cye as luminous lines of substantially the width of the grooves. S5 l It is understood that` when the intensity of the light admitted through the objective end of the telescope or otherwise passing the hair-lines thus formed is greater than that of the light einittedby the hair-lines, the latter appear relatively dark by contrast. When, however, the quantity of light received through the objective is comparatively siiiall, as at night, the luminosit-y of The grooves 7 may be brought une er the rions ways. One simple way is indicated in detail in Fig. :2. The grooves 7 are formed jin that face ofl plate 6 which is turned toward-.the objective or away from the ocularend and .filled with a radium-luminous compound to any desired degree. In such case the luminous compound is directly visible. The amount or quantity of such compound determines. for grooves of the same character, the 'd'egrce-4 of luminosity, whereby l 110 i liancy of t material in the fgrooves 7, I may place it on the periphery o he glass disk 6, as shown in Fig. 3. The glass disk 6 is shown mounted in the tube 10. Adjacent the periphery of saV .of the glass disk 6.

the disk 6 the tube 10 is provided with a circular recess or channel 11 to receive the radium-luminous compound in powdered form.

An abutting ring 12 is tightly fitted against the glass disk 6 to hold it in place and simuitaneousl close the open side of the ress 11 to thereby secure the radium-luminous compound in place. In this case the rays of light emanating from the luminous material are reflected from the walls of the grooves in the form of a narrow band.

Instead of confining the radium-luminous material in the recess 11 mechanically sepa"v rate from the glass disk 6', the luminous ma '-.terial may be attached. to the glass body itself in the form of a coat or may be coated Y .on the mount. as A In Fig. 3 the radium-luminous material is shown as surrounding the whole periphery t is suiiicient, however, for the operation of my device to place a small quantity on any desired int of the periphery, preferably midway o a quadrant efined by the grooves, as shown in Fig. 4, or on several points, preferably` uniformly hpaced, as shown in Fig. 5. In ig. 4, 16 incates the glass disk, 13 a quantity of ra. diam-luminous material, 14 a. ring on which the disk 16 is mounted and 15 a recess in the` ring 14 to receive the luminous material 13A which is confined between the peri he of the disk 16, the tube 17 and the wa s o the recess 15. In Fig. 5 the ring 24 is shown asV provided with four recesses 25 to receive radium-luminous material.

In Fig. 6 the gla disk 36 is shown as beveled along its periphery so that the ra dium-luminous'material may be confined in the space defined by the bevel surface 37, the

wall of the tube 38 and the ring 34.

There is considerable latitude as to the l disposition of the radium-luminous material. en W1 iile rhaps a more .uniform distribution of the uminous'material is conducive to a more perfect illumination, the dis .ition made as shown in Fig. 4 gives entire y satis- In act the position of the luminous ma.

of the hairines also. A. as a roughened lor relatively.

- means a narrow band 22 of the coating n Iv."..i,sog,asa

teria] may be changed at will. so lon as lthe grooves or e uivaleiit means can be rought under its in uence.

In the execution of the invention shown in Figs. 4 and 5 it is advantageous to silver those portions of the periphery which are not covered by the luminous material as in known forms of luminous cross-hairs.

Hair lines formed by grooves and illumi nated b electric bulbs' are known. However suc air lines are incapable of refiecting a sufficient quantity of lig any practical extent when illuminated by radium-luminous material, because the emissive wer of such illuminant is considerabl smal er than that 0f an electric filament. I have found, however, that it is nevertheless possible to roduce visible hair lines in the manner in icated by making the grooves sufficiently deep. By ordinary methods it is impossible to make the grooves of sufficient depth Yto produce practical results.

Fig. 7 illustrates one method of forming relatively deep grooves in a lass body. The plate 20 is first covered wit a thin film of acid resisting material 21, preferably transparent bakelite. Then by any suitable is ate removed to define a line on lthe glass is of the desired width, say .001 inch.

t to be visible to line or band is exposed to the action of hydrofluoiic acid as a liquid or vapor. I have 4found that the best results are obtained by ranking the time of exposure short, then removing the film of bakelite altogether, recoating the whole surface, removin again a narrow band of the coating in t e same position as before and repeating the etching process as before. This cycle of operation may be repeated until the groove formed has the desired characteristics.

While it may be' possible to employ other methods for forming relatively deep grooves in a glass body, I have found the process just.

described as the only solution o the problem. In practice I prefer to use as a protecting .Coating transparent bakelite lacquer which enables me to make a very thin film on the lass disk, a feature of considerable practica importance.

ico

ics

The cycles of operation are in practice as follan-vs: coating, drawing the lines, exposing to the acid fumes, exposing to ammoniacal fumes to neutralize the acid, washing Voff the coating and so on.

The time of exposure to the acid I choose as follows:

" 5 seconds after the first and second coatmg; 10 seconds after the third coating;

20 seconds after the fourth, fifth and sixth coating. The glass disk is preferably held i" from the surface of the acid. Y It is underrwcd that the strength of the 4and a .the ob1eets of my invention. 4scribed is merely for the purpose of outlinacid, the time of exposure and the distance may be varied to some extent, especially for etching different kinds of glass.

By the foregoing description I have not attempted to cover all possible'constructions l available processes for carrying out What 'is deing briefly some constructions and one method to explain the principles on which the invention is based. I have referred to grooves in the surface of the glass disk or other transparent body merely as a convenient means for the particular purpose. It is obvious that lines capable of emitting light under the action of-a radilun-lumiuous material maybe defined by deposition of material on the glass, as for instance bv photogra hic processes which are well un( erstood.

'Ixhe expression'relatively deep grooves in the claims is intended to designate grooves "of the grooves heretofore used for hair-lines.

whose depth is appreciably greater than that defining I clainu- 1. A luminous sign comprising a transparent body, a relatively deep and narrow groove in a surface thereof defining a hairline and a radium luminous substance to make said hair-line visible.

2. A body ofglass, a relatively 'deep and l narrow groove 1n a surface thereof defining a hair-line and a radium-luminous substance to make said hair-line visible.

3. A glass plate, having a relatively deep and narrow groove in a surface thereof defining a hair-line and a radium-luminous substance disposed along the edge of the said glass lplate.

4. glass disk, a relatively deep and narrow groove in a surface thereof andy a ra.-

dium luminous substance disposed along substantially the whole periphery thereof.

5. The combination with au optical nstrument, of a transparent body, relatively 'deep and narrow grooves in a surface thereof defining hair-lines and a radium luminous substance to make said hair lines visible.

6. The. combination with an optical instrument, of a glass plate, a relatively deep and narrow groove in a surface thereof defining a line of reference and a radiumluminous substance to make said line visible.

't'. The combination withV an optical instrument, of a glass late in an image plane thereof, a relatively ee and narrow groove in a surface thereof to define a hair-line and a radium-luminous substance to make said hair-line visible.

9. The combination with an optical instrument, of a glass plate in an image'plane thereof, relatively deep and narrow grooves in a surface thereof to define hair-lines and a radiuni-luminous substance distributedV deep and narrow grooves in the plate, a recess adjacent the edge of the glass plate, and radium-luminous material in said recess.

In testimony whereof, I afiix my signature.

CONRAD FRIEDRICH.

of said disk topmake' 

